PURPOSE: To provide an RC power source filter of small size at low cost by providing a circuit constitutional component functioning as a resistant element in series with an output circuit and providing a capacitor between one terminal of the circuit constitutional component and the ground.
CONSTITUTION: This power source filter is provided between a DC power source 2 and a DC brushless motor drive control circuit 4. The source electrode of a FET 11 is grounded via a first capacitor 12, and the drain electrode of the FET 11 via a second capacitor 13. The filter 3 forms a filter circuit for π-type high-frequency elimination utilizing on-resistance between a source and a drain when the FET 11 is energized by the FET 11, the capacitors 12, 13. The on- resistance value of the FET 11 is around several mΩ, and the level of switching noise generated in the circuit 4 can be reduced to nearly the half on a DC power source 2 side by selecting each value of the capacitors 12, 13 at around 820μF.
OSAWA HIROSHI
GUNJI YOSHIHIDE
